Separation of naphthenes from hydrocarbon mixtures using 7 a. to 12 a. molecular sieves



United States Patent SEPARATION OF NAlHTHENES FROM HYDRO- CARBON MHXTURES USING 7 A. TO 12 A. MO- LECULAR SIEVES Raymond N. Fleck, Albany, and Carlyle G. Wight, Fullerton, Calif., assignors to Union Oil Company of California, Los Angeles, Calif, a corporation of Qalifornia No Drawing. Filed Apr. 5, 1963, Ser. No. 270,306 20 Claims. ((11. 208310) This invention relates to the separation of hydrocarbon mixtures and in particular concerns an improved process for separating naphthenic hydrocarbons from non-naphthenic hydrocarbons.

:In the refining of petroleum by modern techniques, complex hydrocarbon mixtures of the gasoline boiling range are frequently produced which comprise parafiin and naphthene hydrocarbons. The latter have appreciably higher octane numbers than parafiins of the same boiling range, and are hence particularly desirable for use as blending stocks for motor fuels. \Certain naphthenes, particularly cyclohexane, are also of great value in the production of a variety of organic chemicals. At the present time, however, conventional methods for separating naphthenes from complex hydrocarbon mixtures are either economically impractical or are effective only with particular mixtures.

It is accordingly an object of this invention to provide an improved process for separating naphthenic hydrocarbons from complex hydrocarbon mixtures.

A further object is to provide a process for separating naphthenes from non-naphthenic hydrocarbons of substantially the same boiling point.

Another object is to provide a process for improving the anti-knock rating of hydrocarbon mixtures which comprise naphthenic and non-naphthenic hydrocarbons of the gasoline boiling range.

Other and related objects will be apparent from the following detailed description of the invention, and various advantages not specifically referred to herein will be apparent to those skilled in the art upon employment of the invention in practice.

We have now found that the foregoing objects and their attendant advantages can be realized in an adsorptive separation process in which a complex hydrocarbon feed mixture comprising naphthenic hydrocarbons is contacted with a molecular sieve type adsorbent. More particularly, we have found that naphthenic hydrocarbons can be separated from paraffins as Well as aromatic hydrocarbons by a process which comprises: (1) contacting a fluid hydrocarbon mixture with a lean molecular sieve adsorbent to obtain a rich adsorbent containing a large proportion of the non-naphthenic components of the feed mixture and a non-adsorbed phase enriched in the naphthene components, (2) separating the rich adsorbent from the non adsorbed phase, and (3) treating the rich adsorbent to desorb the non-naphthenic hydrocarbons therefrom and return the adsorbent to a lean state for re-use in the next succeeding cycle of operation.

Considering now the process of the invention in further detail, it is generally applicable in the vapor phase to complex hydrocarbon mixtures of the gasoline boiling range comprising naphthenic hydrocarbons containing 5 or 6 carbon atoms, e.g., cyclopentane, cyclohexane, and methyl cyclopentane. The lowest boiling parafiin in the hydrocarbon feed mixture should boil no more than about F. below the boiling point of the naphthene compo- 3,l82,0i? Patented May 4, 1965 nent for the vapor phase embodiment of the invention to be effective, and preferably the paraffin component has a boiling point less than about 15 IF. below the naphthene component being separated. The liquid phase embodiment of the process of our invention is generally applicable to hydrocarbon mixtures of the gasoline boiling range comprising naphthenic and non-naphthenic hydrocarbons, i.e., to mixture boiling over the range between about and about 400 F. and comprising naphthenic and non-naphthenic components ranging in molecular weight from about C to about C Preferably, the liquid phase feed mixture has a Wide boiling range of at least about 100 F. and typically has an initial boiling point of about 100 F. and a final boiling point of about 400 F. or higher, e.g., a full range aviation gasoline. Usually, of course, such hydrocarbon mixtures are of petroleum origin, but they may also be derived from coal tar, tar sand, oil shale, or other sources. Typical feed mixtures to the process include fractions from straightrun gasolines, thermally and catalytically cracked gasolines, reformates, isomerizates, etc. :In general, the straight-run and cracked feeds will comprise substantially only naphthenic and parafiinic hydrocarbons, and the separation effected is one of separating naphthenes from parafl'iins. Reformates, on the other hand, comprise appreciable amounts of aromatic hydrocarbons. One of the features of the present process lies in its ability to separate naphthenes from both paraffins and aromatics. A particular advantage of the process of our invention is that the liquid phase separation of naphthenes is effectively accomplished on gasoline fractions of very wide boiling range, i.e., having a boiling range from about 100 F. to about 400 F. or higher. A further advantage is found in the fact that complete separation is attained regardless of the relative proportions of naphthenic and non-naphthenic hydrocarbons in the feed mixture. 'Either the more readily adsorbed non-naphthenic hydrocarbons or the less readily adsorbed naphthenic hydrocarbons can be the major component of the feed mixture with equally effective separation being accomplished.

The absorbent employed in the present process is a molecular sieve, preferably having a pore size between about 7 A. and about 12 A., such as is described in British Patent No. 777,233. As a class, molecular sieve adsorbents are crystalline partially dehydrated zeolitic metallo alumino silicates having pores of substantially uniform diameter which can vary from as little as 3 A. to 15 A. or greater, depending upon the identity and proportion of the component elements. Of these materials there are two principal commercial types, the so-called Type A and Type X," which differ in their X-ray diffraction patterns, apparent densities, and other characteristics. Both types have been used to separate substances of different molecular size and shape, and it is generally considered that the adsorptive selectivity of molecular sieves is due to their containing uniform pores Whose diameter is of molecular magnitude. Thus, the ability of amolecular sieve whose pore diameter is about 5 A. to separate straight-chain parafiins from branch-chain paraifins is considered to be due to the fact that the maximum molecular dimension of the straight-chain parafiins is somewhat less than 5 A., whereas that of the branched-chain parafllns is somewhat greater than 5 A. Consequently, the smaller straight-chain molecules can enter and be held in the pores of the 5 A. sieve, whereas the branched-chain molecules are too large to enter pores of such small size. In the present process, however, the absorbent cannot operate in such manner since the pore size is greater than the minimum molecular dimension of any of the parafiinic, napthenic, or aromatic hydrocarbons present in the feed stream. On the other hand, it does not operate as a conventional adsorbent or even as would be expected from the teachings of the aforesaid British Patent No. 777,233. The latter clearly teaches that the Type X molecular sieves preferentially adsorb polar, polarizable, and unsaturated molecules and reject non-polar and saturated molecules. From such teach ing it would be expected that aromatics would be adsorbed in preference to naphthenes and paraffins and that naphthenes would be adsorbed in preference to paraifins. As is hereinafter shown, however, we have found that in the present process, both parafiins and aromatics are adsorbed in preference to the naphthenes.

As stated, the adsorbents which are employed in accordance with the invention are zeolitic partially dehydrated metallo alumino silicates having pores of a substantially uniform diameter between about 7 A. and about 12 A. Certain naturally occurring minerals can be heated to dehydrate the molecule and obtain an activated zeolitic adsorbent of such type. However, we greatly prefer the synthetic materials which are conveniently prepared by heating suitable quantities of alumina and silica with an excess of sodium hydroxide and thereafter washing out the excess caustic to obtain a Type X zeolitic sodium alumino silicate having the approximate molecular structure [6Na O-6Al O -15SiO on a water-free basis, and having a uniform pore diameter of about 13 A. The uniform pore diameter of this product can be altered by exchanging part of the sodium cation with other metals. For example, such product can be treated with a concentrated solution of a calcium salt, e.g., calcium chloride, at superatmospheric pressure and at 20-17*5 C., washed with water to remove excess calcium chloride, and thereafter partially dehydrated by heating to obtain a Type X calcium sodium alumino silicate having a pore diameter of about 10 A. and having an average molecular structure on a water-free basis corresponding to Other divalent cations such as magnesium, strontium, barium, beryllium, zinc, cobalt, nickel, and the like can be employed instead of calcium. Other monovalent metals such as potassium, silver, cesium, etc., may be used instead of sodium. Further details regarding the properties and preparation of Type X molecular sieves are to be found in British Patent No. 777,233. While any molecular sieve having a pore diameter between about 7 A. and about =12 A. can be employed in accordance with the preferred embodiment of the invention, it is further preferred to use a 10 A. pore size calcium sodium alumino silicate such as referred to above. This particular product is available commercially from Linde Company, Tonawanda, New York, under the trade name Molecular Sieves 10X. The sodium salt described above is also available from the same company, under the trade name Molecular Sieves 13X. These commercial materials can contain substantial amounts of inert binder materials.

The optimum particle size of the adsorbent will depend upon the manner in which it is used in the process, i.e., as a fixed compact bed, a fluidized bed, etc., but is usually between about 2 and about 400 mesh, preferably between about 4 and about 30 mesh for fixed and moving compact beds and between about 100 and about 300 mesh for fluidized beds.

The adsorbent is preferably employed in the form of a dense compact fixed or moving bed which is alternately contacted with the feed and then desorbed. In the simplest embodiment of the invention, the adsorbent is employed in the form of a single static bed, in which case the process is only semi-continuous. Preferably, a set of two or more static beds is employed in fixed-bed contacting with appropriate valving so that the feed stream is passed through one or more adsorbent beds while the desorption is carried out in one or more of the other beds in the set. The direction of flow during adsorption and desorption can be either up or down through the adsorbent, but preferably the adsorption is carried out in one flow direction and the desorption in the other. Any of the conventional apparatus employed in static bed fluidsolids contacting can be used. A moving compact bed of adsorbent has a much greater separation efficiency than a fixed compact bed of the same size because of the ability of the former to provide reflux. The moving compact bed is therefore preferable when an extremely high degree of separation is desired or when the feed mixture separation factor is poor.

In one embodiment of the invention the hydrocarbon feed mixture is contacted with the adsorbent in the vapor phase. Thus, the temperature is at least as high as the dew point of the feed mixture at the particular pressure employed. The pressure is usually near atmospheric but can be either subatmospheric or superatmospheric. In general the adsorption is carried out at a temperature between about 0 F. and about 800 F., preferably between about F. and about 650 F., and usually at pressures between about atmospheric and about 1,000 p.s.i.g., preferably between about 0 p.s.i.g. and 200 p.s.i.g. The immediate products of the initial adsorption step are: (1) a non-adsorbed vapor phase which is rich in the naphthenic components of the feed mixture and lean in paraffins and aromatics, and (2) a solid rich adsorbent containing adsorbed paraffins and aromatics and lean in naphthenes. The solid and vapor phases are separated, and the latter is passed to storage as the purified naphthene product of the process. The rich adsorbent, on the other hand, is treated to desorb the hydrocarbons therefrom and to return it to a lean state for reuse. According to one mode of operation, such treatment merely comprises subjecting the rich adsorbent to an elevated temperature and/ or a reduced pressure, i.e., when the initial adsorption step is carried out at, say, 300 F. and 75 p.s.i.g., the adsorbed component can be effectively recovered by heating the rich adsorbent to, say 650 F. and/ or reducing the pressure to 0 p.s.i.g. or less. The use of elevated temperature can also be combined with the use of a stripping gas in the known manner.

In another embodiment of the invention, the hydrocarbon feed mixture is contacted with the adsorbent in the liquid phase. The temperature and pressure should be correlated accordingly. In general, the adsorption is usually carried out at a temperature between about 0 F. and about 800 F. and at a pressure between about 0 p.s.i.g. and about 1,000 p.s.i.g., preferably at a temperature between about 50 F. and about 300 F. and at a pressure between about 0 p.s.i.g. and 200 p.s.i.g. The immediate products of the initial adsorption step are (1) a liquid non-adsorbed phase which is rich in the naphthenic components of the feed mixture and lean in the non-naphthenic components, e.g., parafiins and aromatics, and (2) a solid rich adsorbent containing adsorbed nonnaphthenic compounds and lean in naphthenes. The solid and liquid phases are separated, and the latter is passed to storage as the purified naphthene product of the process. The rich adsorbent, on the other hand, is treated to desorb the non-naphthenic hydrocarbons therefrom and to return it to a lean state for re-use. In accordance with one mode of operation, such treatment merely comprises subjecting the rich adsorbent to an elevated temperature and/or reduced pressure. For example, when the initial adsorption step is carried out at 200 F. under 100 p.s.i.g., the adsorbed components can be effectively recovered by heating the rich adsorbent to 600 F. and/ or reducing the pressure to 0 p.s.i.g. or less. The use of elevated temperatures and/or reduced pressures may also be combined with the use of a stripping fluid in the known manner.

In accordance with a preferred mode of operation, the rich adsorbent is treated With a suitable displacement exchange fluid at approximately the same temperature as that employed in the initial adsorption stage. The displacement exchange fluid can be any material which is inert with respect to the adsorbent and the feed mixture, which is adsorbable by the adsorbent, and which is readily separated from the components of the feed mixture by distillation, absorption, or other conventional means. Preferably, the displacement exchange fluid is one which has a boiling point substantially outside the boiling range of the feed mixture and has an adsorbability substantially the same as that of the adsorbed components of the feed mixture. Preferred displacement exchange fluids are ammonia and paraflin hydrocarbons boiling sufliciently below the feed mixture, i.e., containing no more than 5 carbon atoms, so as to make them easily separable from both the adsorbed and non-adsorbed phases by distillation, e.g., iso-pentane, n-pentane, iso-butane, n-butane, and the like. Other materials which can be employed include the nolefins, iso-olefins, l-chloro-alkanes, l-bromo-alkanes, 1- fluoro-alkanes, alpha-omega-dihalo-alkanes, n-alkyl amines, di-n-alkyl amines, di-n-alkyl sulfides, di-n-alkyl oxides, and the like.

The following experimental examples, I to XIII, in which percentages are by volume, specifically illustrate the practice of the invention in the vapor phase.

EXAMPLE I A naphthenic gasoline is fractionated to separate a cut boiling in the range of 165 1 .-185 F. Forty volumes of this cut, consisting of 82 percent naphthenes, 15 percent iso-paraffins, and 3 percent benzene, is passed through a lean adsorbent bed of Molecular Sieves 10X (zeolitic calcium sodium alumino silicate) at a temperature of about 392 F. and atmospheric pressure. The effluent is collected in a series of small portions or cuts, each containing about 3 volumes. All of the feed is added by the time the third cut is collected. Steam is then passed through the bed in the same flow direction while collecting efliuent cuts 4 to 13. The steam stripping is carried out without changing the temperature or pressure. Table 1 gives the composition of effluent cuts 1 to 13 illustrating the separation obtained.

Table 1 Composition Ont No. Volume Naphthene (volume Benzene of Cut percent) iso-Parafims 3.0 2. 9 3. 5 100 Steam stripping started) EXAMPLE II A feed mixture comprising 71 percent naphthencs, 19 percent normal paraflins, and percent benzene is passed over a lean adsorbent bed of Molecular Sieves 10X at about 392 F. and one atmosphere pressure. Forty volumes of the feed (boiling range 161 F.-165 F.) is introduced to the bed during the first three eflluent cuts, then steam stripping in the same flow direction as feed flow is begun and cuts 4 to 14 are taken. Table 2 illustrates the selective vapor phase adsorption of the normal paraflrns and benzene which produces an essentially pure naphthene (cyclohexane and methylcyclopentane) effluent stream.

EXAMPLE III Table 3 Composition Cut No. Volume Naphthenes volume Benzene of Cut percent) Paraflins EXAMPLE IV In an experiment conducted in the same manner and with the same feed as Example I, except that silica gel is substituted for the Molecular Sieves 10X adsorbent bed, the composition of the effluent cuts is essentially the same as that of the naphthenic feed mixture. Thus, no separation of the components occurs. Repetition of the experiment at F., again yields an effluent with substantially the same paraflin-naphthene ratio as exists in the feed mixture.

EXAMPLE V Another experiment, conducted in the same manner and with the same feed as Example III, except activated carbon is substituted for the Molecular Sieves 10X adsorbent bed, yields efliuent cuts having essentially the same paraflin-naphthene ratio as the feed fraction. This same experiment, repeated at a temperature of about 100 F., also shows essentially no separation of the naphthenic and paraflinic hydrocarbons from each other.

EXAMPLE VI Another run, conducted in the same manner and with the same feed as Example III with the exception that the temperature of contacting and stripping is lowered from about 392 F. to about 225 F., yields an essentially pure naphthene effluent through out 8, and cuts 9 to 12 have compositions similar to those cuts in Example III, as shown in Table 3.

7 EXAMPLE v11 This run, conducted in the same manner and with the same feed as Example II except that a pressure of 100 p.s.i.g. is maintained during adsorption and stripping, yields substantially the same naphthene-parafiin separation as shown in Table 2.

EXAMPLE VIII In another run, a Type X strontium sodium alumino silicate is substituted for the Molecular Sieves 'lOX (calcium sodium alumino silicate) in an experiment con ducted in the same manner" and with.the same feed as Example III. The naphthenes are separated from the paraffins and benzene in substantially the same manner as shown in Table 3.

EXAMPLE IX A five volume hydrocarbon mixture comprising 42 percent 2,4-dimethylpentane and 58 percent cyclohexane is circulated for a period of 60 minutes through a lean Molecular Sieves X adsorbent bed at about 392 F. and one atmosphere pressure. The unadsorbed phase contains 38 percent 2,4-dimethylpentane. The rich adsorbent is then stripped with steam at 392 F. and atmospheric pressure, yielding 1.5 volumes of hydrocarbon adsorbate which contains 50 percent cyclohexane.

EXAMPLE X Another run, conducted in the same manner and with the same feed as Example DC, except that ammonia is used for stripping, yields a hydrocarbon adsorbate of substantially the same amount and composition as found in Example DC.

EXAMPLE XI This run, conducted in the same manner and with the same feed as Example IX except that iso-pentane is used for stripping, yields a hydrocarbon adsorbate of substantially the same amount and composition as found in Example IX.

EXAMPLE XII A five volume hydrocarbon mixture comprising 49 percent cyclopentane and 51 percent 2,2-dimethylbutane is circulated for a period of 60 minutes through a lean Molecular Sieves 10X adsorbent bed at about 392 F. and one atmosphere pressure. The unadsorbed phase, lean in 2,2-dimethylbutane, contains 54 percent cyclopentane. The rich adsorbent is steam stripped at 392 F. and one atmosphere producing 1.2 volumes of a hydrocarbon adsorbate which contains 61 percent 2,2-dimethylbutane;

EXAMPLE XIII Another five volume hydrocarbon mixture comprising 47 percent n-hexane and 53 percent methylcyclopentane is circulated for one hour through a lean Molecular Sieves 10X adsorbent bed at about 392 F. and one atmosphere pressure. The methylcyclopentane is less selectively adsorbed and the unadsorbed phase contains 43 percent n-hexane. A 1.8 volume adsorbed hydrocarbon phase, desorbed by steam stripping the rich adsorbent, contains 53 percent n-hexane.

The following Examples XIV to XV IH, in which percentages are by volume, specifically illustrate the practice of the invention in the liquid phase.

EXAMPLE XIV Forty volumes of a full range aviation gasoline consisting of 41 percent parafiins, 5 percent C -C aromatics, and 54 percent mononaphthenes is passed in liquid phase through a lean adsorbent bed of a -45 mesh Molecular Sieves 10X (calcium sodium alumino silicate) at a temperature of about 72 F. and atmospheric pressure. The analysis of the first unadsorbed fraction or raflinate cut, amounting to ten volumes of the initial charge, has a composition of percent paraflins and 60 percent naphthenes. The second ratfinate cut often volumes has a composition corresponding to about 38 percent parafiins and about 62 percent naphthenes. Thus, the ratio of naphthenes to paraflins increases from 1.32/ 1.00 in the feed to l.50 /1.00 in the first cut and to 1.63/1.00 in the second out which illustrates the highly selective adsorption of the paraffius in the liquid phase contacting of this invention.

The rich adsorbent is then liquid phase contacted with benzene without changing the temperature or pressure yielding an extract phase rich in adsorbed aromatics and paraffins.

EXAMPLE XV In another run conducted in the same manner and with the same feed as Example XIV, except that the temperature is raised from 72 F. to 200 F. and the pressure is raised from atmospheric to 100 p.s.i.g., the composition of the rafiinate cuts is essentially the same as that found in Example XIV and a corresponding substantial paraflin enrichment of the extract phase is also observed.

EXAMPLE XVI In an experiment conducted in the same manner and with the same feed as Example XIV, except that activated carbon is substituted for the Molecular Sieves 10X adsorbent bed, the raffinate naphthene-parafiin ratio is essentially the same as that of the naphthenic feed mixture. Thus, there is no separation of these components.

EXAMPLE XVII Another experiment conducted in the same manner and with the same feed as Example XIV, except that silica gel is substituted for the Molecular Sieves 10X adsorbent bed, yields a rafiinate having essentially the same naphthene-parafiin ratio as the feed fraction. Again, there is no selectivity shown on silica gel between the naphthene and parafiin hydrocarbons.

EXAMPLE XVIII In this run, the unadsorbed or raffinate phase of Example XIV is reprocessed in the same manner as the original feed and a correspondingly higher naphthene concentration is obtained in the resulting raflinate phase. The final naphthene concentration is about percent after nine successive stages of treatment.

The present class of adsorbents has relatively strong adsorptive aflinity toward highly polar compounds, e.g., ethers, thioethers, water, alcohol, mercaptans, heterocyclic nitrogen or sulfur compounds, etc. The presence of such compounds in the feed stream may more or less interfere with the adsorption process of the invention, and preferably they should accordingly be removed prior to contacting the feed with the adsorbent. Such removal can be effected in various ways, e.g., by contacting the feed with an inorganic halide such as copper chloride, calcium chloride, magnesium chloride or the like, or with a suitable partially dehydrated metallo alumino silicate. Although the deactivation of the adsorbent is gradual, some deactivation can eventually occur. It is within the scope of this invention to reactivate the silicate adsorbent in any conventional manner, e.g., by high temperature contacting with a hot reactivating gas such as flue gas, air, etc.

As will be apparent, the process of the invention essentially comprises solids-fluid contacting operations, and any of the various techniques and equipment conventionally applied to such type of operation can be adapted to the practice of the invention without departing from the scope thereof. Thus, while it is often preferred to maintain the adsorbent in the form of a moving bed, i.e., as a solids-fluid contacting operation in which a compact bed of the adsorbent is passed successively through adsorption and desorption zones where it is concurrently or countercurrently contacted with the feed stream and the displacement exchange fluid, respectively, the process is, nevertheless, operable in the form of a fixed compact bad. Also, the solids-fluid contacting operation can be carried out employing fluidized techniques whereby the adsorbent is employed in relatively small particle size and is suspended by the flow of the fluid with which it is contacted. Other adaptable techniques and modification will be apparent to those skilled in the art.

In the foregoing specification and in the appended claims, the material to which the process of the invention is applied is described as a hydrocarbon mixture comprising certain hydrocarbon components. It is to be understood, however, that the term is meant to include mixtures of hydrocarbons containing small normally incident amounts of nitrogen, sulfur, and oxygen components.

This application is a continuation-in-part of our prior co-pending applications Serial No. 746,601, filed July 7, 1958, now abandoned, and Serial No. 775,734, filed November 24, 1958, now abandoned.

Other modifications and adaptations which would occur to one skilled in this particular art are to be included in the spirit and scope of this invention as defined by the following claims.

We claim:

1. A process for separating a fluid hydrocarbon mixture comprising naphthenic and non-naphthenic hydrocarbons which comprises: contacting said hydrocarbon mixture with a solid granular adsorbent comprising a partially dehydrated crystalline zeolitic metallo alumino silicate having pores of substantially uniform diameter between about 7 A. and about 12 A. whereby there is obtained a rich adsorbent containing adsorbed hydrocarbons and an unadsorbed fluid raffinate product; and separating said rich adsorbent from said unadsorbed liquid rafiinate product, said unadsorbed liquid rafiinate product being substantially leaner in non-naphthenic hydrocarbons than said hydrocarbon mixture.

2. A process as defined in claim 1 wherein said adsorbent has a pore diameter of about 10 A.

3. A process as. defined in claim 1 wherein said rich adsorbent is treated to remove adsorbed hydrocarbons therefrom.

4. The process for separating a hydrocarbon mixture comprising naphthenes containing from about 5 to about 6 carbon atoms and paraflins which are difficult to separate therefrom by distillation, which comprises: 1) contacting said mixture in the vapor phase with a lean granular adsorbent comprising a partially dehydrated metallo alumino silicate having pores of substantially uniform diameter between about 7 A. and about 12 A., said contacting being effected at a temperature below about 800 F., whereby there is obtained a rich adsorbent containing adsorbed parafiins and a raflinate product which is rich in naphthenes; (2) separating sid raflinate product from said rich adsorbent; and (3) treating said rich adsorbent to remove adsorbed parafins therefrom.

5. A process according to claim 4 wherein the said adsorbent comprises a calcium sodium alumino silicate having substantially uniform diameter pores of about A.

6. A process as defined by claim 4 wherein, in Step (3), said rich adsorbent is contacted with a displacement exchange fluid to obtain an extract product comprising said desorbed paraffins and said displacement exchange fluid and said extract product is treated to separate said displacement exchange fluid therefrom.

7. A process for separating cyclopentane from a hydrocarbon mixture comprising cyclopentane and paraflin hydrocarbons boiling no more than F. below said cyclopentane, which process comprises: (1) contacting said hydrocarbon mixture in the vapor phase with a lean granular adsorbent comprising a partially dehydrated crystalline zeolitic calcium sodium alumino silicate having substantially uniform diameter pores of about 10 A., said contacting being effected at a temperature between about 100 F. and about 650 F. and at a pressure between about 0 p.s.i.g. and about 200 p.s.i.g., whereby there is obtained a rich adsorbent containing adsorbed parafiin components of said mixture and a raffinate product which is rich in cyclopentane; (2) separating said rafiinate product from said rich adsorbent; and (3) treating said rich adsorbent to desorb the adsorbed parafiin therefrom.

8. A process as defined by claim 7 wherein, in Step (3), said rich adsorbent is contacted with a displacement exchange fiuid to obtain an extract product comprising said desorbed paraflins and said displacement exchange fluid and said extract product is treated to separate said displacement exchange fluid therefrom.

9. A process for separating naphthenes containing 6 carbon atoms from a hydrocarbon mixture comprising said naphthene and parafiin hydrocarbons boiling no more than 20 F. below said naphthenes, which process comprises: (1) contacting said mixture in the vapor phase with a lean granular adsorbent comprising a partially dehydrated crystalline zeolitic calcium sodium alumino silicate having substantially uniform diameter pores of about 10 A., said contacting being effected at a temperature between about 100 F. and about 650 F. and at a pressure between about 0 p.s.i.g. and about 200 p.s.i.g., whereby there is obtained a rich adsorbent containing adsorbed paraliin components of said mixture and a rafiinate product which is rich in said napthenes; (2) separating said raftinate product from said rich adsorbent; and (3) treating said rich adsorbent to desorb said adsorbed parafiins therefrom.

10. A process as defined by claim 9 wherein, in Step (3), said rich adsorbent is contacted with a displacement exchange fluid to obtain an extract product comprising said desorbed parafiins and said displacement exchange fluid and said extract product is treated to separate said displacement exchange fluid therefrom.

11. A process for the separation of cyclohexane from a saturated hydrocarbon fraction boiling in the range from about 75 C. to about C. which comprises passing the fraction through a mass of Type X synthetic zeolite of about 10 A. units pore diameter, recovering as effluent a stream enriched in cyclohexane relative to the fraction charged, discontinuing passage of additional mixture to the sorbent mass after an amount has been charged which is sufficient to substantially reduce the capacity of the sorbent to resolve addition-a1 portions of said mixture, and thereafter desorbing the remaining hydrocarbons from said sorbent mass.

12. The process for upgrading a wide boiling range hydrocarbon mixture comprising napht-henic and nonnaphthenic hydrocarbons boiling within the gasoline boiling range, which comprises: contacting said hydrocarbon mixture in liquid phase with a solid granular adsorbent essentially comprising a partially dehydrated crystalline zeolitic metallo alumino silicate having pores of substantia'lly uniform diameter between about 7 A. and about 12 A. whereby there is obtained a rich solid adsorbent containing adsorbed hydrocarbons and an unadsorbed liquid raflina-te product; and separating the rich solid adsorbent from the unadsorbed liquid rafiinate product, said unadsorbed liquid raffinate product being substantially richer in naphthenic hydrocarbons than said hydrocarbon mixture.

13. The process for upgrading a hydrocarbon mixture comprising naphthenic and non-naphthenic hydrocarbons boiling within the gasoline boiling range, which comprises: 1) contacting said hydrocarbon mixture in the liqud phase with a solid granular lean adsorbent essentially comprising a partially dehydrated crystalline zeolitic metallo alumino silicate having pores of substantially uniform diameter between about 7 A. and about 12 A., said contacting being effected at a temperature below about 800 F. whereby there is obtained a rich adsorbent containing adsorbed non-naphthenic hydrocarbon com- 1 1 ponents of said mixture and a rafiinate product which is rich in the naphthenic hydrocanbon components of said mixture; (2) separating said raflinate product from said rich adsorbent; (3) treating said rich adsorbent to desorb said adsorbed non-naphthenic hydrocarbons therefrom.

14. A process as defined by claim 13 wherein said adsorbent comprises a partially dehydrated crystalline calcium sodium alumino silicate having substantially uniform pores of about 10 A. in diameter.

15. The process for treating a wide boiling range hydrocarbon mixture of the gasoline boiling range comprising naphthenic and non-naphthenic hydrocarbons, which process comprises: (1) contacting said hydrocarbon mixture in the liquid phase with a solid granular lean adsorbent essentially comprising a partially dehydrated crystalline metallo alumino silicate having pores of substantially uniform diameter between about 7 A. and about 12 A., said contacting being effected at a temperature between about 50 F. and about 300 F. and a pressure between about p.s.i.g. and about 200 p.s.i.g. whereby there is obtained a rich adsorbent containing adsorbed non-naphthenic hydrocarbons and a raflinate product which is rich in naphthenes; (2) separating said r-affinate product from said rich adsorbent; and (3) treating said rich adsorbent to recover said adsorbed non-naphthenic hydrocarbons therefrom.

16. A process according to claim 15 wherein the metal of said metallo alumino silicate adsorbent is predominantly a divalent metal.

17. A process according to claim 15 wherein the metal of said metallo alumino silicate adsorbent is predominantly calcium and wherein the pore diameter of said adsorbent is about A.

18. A process as defined by claim wherein, in Step (3), said rich adsorbent is contacted with a displacement exchange fluid to obtain an extract product comprising said desorbed non-naphthenic hydrocarbons and said displacement exchange fluid and said extract product is treated to separate said displacement exchange fluid therefrom.

12 19. A process according to claim 15 wherein said mix-' ture has an initial boiling point not less than about 100 F. and a final boiling point not greater than about 400 20. The process for separating a wide boiling range hydrocarbon mixture comprising naphthenic and nonnaphthenic hydrocarbons, said mixture boiling between about 100 F. and about 400 R, which comprises: (1) contacting said mixture in the liquid phase with a solid granular lean adsorbent essentially comprising a partially dehydrated crystalline zeolitic calcium sodium alumino silicate having substantially uniform pores of about 10 A. in diameter, said contacting being affected at a temperature between about F. and about 300 F. and a pressure between about 0 p.s.i.g. and about 200 p.s.i.g., whereby there is obtained a rich adsorbent having nonnaphthenic hydrocarbons adsorbed thereon and a raflinate product which is rich in naphthenes; (2) separating said raflinate product from said rich adsorbent; (3) contacting said rich adsorbent with a displacement exchange fluid comprising a paraffin hydrocarbon which is readily separable from the components of said mixture, said contacting being aflected at a temperature between about 50 F. and about 300 F. and a pressure between about 0 p.s.i.g. and about 200 p.s.i.g., whereby there is obtained an extract product rich in said non-naphthenic hydrocarbons and a lean adsorbent: (4) separating said extract product from said lean adsorbent; (5) returning said lean adsorbent to Step (1); (6) separately treating said extract and rafiinate products to separate said displacement exchange fluid therefrom; and (7) returning said separated displacement exchange fiuid to Step (3).

References Cited by the Examiner UNITED STATES PATENTS 2,859,256 11/58 Hess et al. 260-676 2,882,244 4/59 Milton 260 -676 XR ALPHONSO D. SULLIVAN, Primary Examiner. 

1. A PROCESS FOR SEPARATING A FLUID HYDROCARBON MIXTURE COMPRISING NAPHTHENIC AND NON-NAPHTHENIC HYDROCARBONS WHICH COMPRISES: CONTACTING SAID HYDROCARBON MIXTURE WITH A SOLID GRANULAR ABSORBENT COMPRISING A PARTIALLY DEHYDRATED CRYSTALLINE ZEOLITIC METALLO ALUMINO SILICATE HAVING PORES OF SUBSTANTIALLY UNIFORM DIAMETER BETWEEN ABOUT 7 A. AND ABOUT 12 A. WHEREBY THERE IS OBTAINED A RICH ABSORBENT CONTAINING ABSORBED HYDROCARBONS AND AN UNABSORBED FLUID RAFFINAE PRODUCT; AND SEPARATING SAID RICH ABSORBENT FROM SAID UNABSORBED LIQUID RAFFINATE PRODUCT, SAID UNABSORBED LIQUID RAFFINATE PRODUCT BEING SUBSTANTIALLY LEANER IN NON-NAPHTHENIC HYDROCARBONS THAN SAID HYDROCARBON MIXTURE. 